The present invention relates generally to a sweetener delivery system and, more particularly, to an artificial sweetener composite that offers a combination of controlled release with improved stability and shelf life.
Numerous patents have disclosed coatings for sweeteners in an attempt to delay or prolong sweetness, as well as to stabilize those sweeteners, such as aspartame, which are sensitive to moisture, temperature and pH. U.S. Pat. No. 4,384,004 to Cea et al. discloses solid particles of aspartame encapsulated by a coating material selected from the group consisting of cellulose, cellulose derivatives, arabinogalactin, gum arabic, polyolefins, waxes, vinyl polymers, gelatin, zein and mixtures thereof, wherein the amount of said coating material to said methyl ester is from 1:1 to 1:10. More particularly, the coating materials include cellulose, methyl cellulose, ethyl cellulose, cellulose nitrate, cellulose acetate phthalate, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, arabinogalactin; polyethylene, polymethacrylates, polyamides, ethylene-vinyl acetate copolymers, polyvinylpyrrolidone; gum arabic, paraffin wax, carnauba wax, spermaceti, beeswax; stearic acid, steryl alcohol, glyceryl stearate; gelatin, zein and mixtures thereof.
The method of coating employed in this reference includes suspending the aspartame particles in a stream of air that passes through a zone of atomized liquid droplets of the coating material, so that the coating material is deposited on the surface of the aspartame. More than one coating may be used, and in such instance, the inner coating is preferably water-soluble and the outer coating is preferably water-insoluble.
U.S. Pat. Nos. 4,122,195 and 4,139,939, both to Bahoshy et al., fix aspartame by preparing it with a material such as gum arabic or the reaction product of a compound containing a polyvalent metallic ion, with an ungelatinized starch acid-ester of a substituted dicarboxylic acid, by a spray drying technique, where the aspartame and a film former are prepared in an emulsion.
U.S. Pat. No. 4,374,858 to Glass et al. discloses an aspartame sweetened chewing gum having improved sweetness stability wherein the chewing gum piece has aspartame coated on its surface, as opposed to incorporating it in the chewing gum mix.
European patent application No. 81110320.0, published June 16, 1982 (Publication No. 0053844) to Ajinomoto Co., Inc., discloses a stabilized dipeptide-based sweetening composition comprising (1) from 20 to 60% by weight of solid fat, (b) from 10 to 30% by weight emulsifier, (c) from 10 to 30% by weight polysaccharide and (d) not more than 30% by weight of dipeptide sweetener. The compositions are prepared by heating the mixture of the ingredients, cooling, and pulverizing to obtain powder or granules of the composition to obtain an ASTM mesh size of smaller than 12. Spray drying the mixture is also disclosed.
U.S. Pat. No. 4,105,801 to Degliotti discloses a confection comprising a core portion and a shell adherently enveloping the core portion, whereby the shell is formed by an intimate mixture of microcrystals of xylitol with a solid fatty substance in a proportion of 0.5 to 15 parts by weight of fatty substance to each 100 parts by weight of xylitol. The fatty substance is preferably a mono-, di- or triglyceride having a melting range of between 20.degree. and 60.degree. C.
U.S. Pat. No. 3,389,000 to Toyonaka et al. discloses protective coatings for granular nucleoside-5-phosphates, the coatings being edible fats melting between 40.degree.-100.degree. C. and derived from plants and animals. Examples of edible fats include hydrogenated oils such as soybean oil, cottonseed oil, almond oil, castor oil, linseed oil, mustard oil, olive oil, grapefruit seed oil, palm oil, palm kernel oil, rapeseed oil, rice bran oil and the like and mixtures thereof. This reference discloses a process of preparing the granular product from a liquid mixture of fats and nucleoside-5-phosphates which are sprayed from a pressure nozzle and the resultant granules cooked and recovered.
U.S. Pat. No. 4,382,924 to Berling discloses liquid oral dosage forms for vitamins or pharmaceutical materials comprising an edible oil, a high potency lipid soluble sweetener such as saccharin and a lipid soluble flavorant. The edible oil may be a polyol fatty acid ester having at least four fatty acid ester groups and each fatty acid having from about 8 to about 22 carbon atoms. The oil, sweetener and flavor oil are mixed and heated and then cooled to provide a palatable liquid dosage form.
For a general discussion of spraying fatty materials onto sweeteners and the like, see U.S. Pat. Nos. 3,949,094 and 3,976,794 both to Johnson and U.S. Pat. No. 3,867,556 to Darragh et al. U.S. Pat. No. 4,293,572 to Silva et al. discloses the application of a dispersion of an emulsified fat with a solution of dextrin, saccharin or a polysaccharide to a food product as a barrier against moisture. U.S. Pat. No. 3,527,647 discloses a process of agglomerating particles by randomly scattering and spraying moistened particles to cause them to collide and form agglomerates.
The problem relating to stabilization of sweeteners such as aspartame, which has not been previously addressed, relates to the wettability of the aspartame crystal as well as to its morphological configuration. As a result, it is very difficult to coat aspartame using ordinary mixing or spray coating techniques. To be effective as protective barriers, coatings must be able to wet and adhere to the crystalline surface, including the needle-like tips and other shape variations of the aspartame. Additionally, the coating must be capable of being applied in a film with a uniform thickness sufficient to provide a barrier against degradative factors such as moisture, pH changes, temperature changes and reactive chemicals. The coatings, in addition to being protective barriers, must be flexible enough to conform to the surface irregularities and geometrical configuration without cracking due to mechanical stresses which it is subjected to during incorporation of the sweetener into specific product applications.
One approach has been to mix known coating materials such as fats, with certain other core materials such as aspartame, however the noted coating materials do not provide adequate protection to keep the core material in a stabilized state. Fats do not provide adequate coating materials, nor do such coating materials as starch and certain other materials such as waxes. Many of these materials require solvents and moisture for application, which have adverse effects on the stability of hydrophilic instable materials such as aspartame.
The process of European patent application No. 81110320.9 (Publication No. 0053844) filed Dec. 10, 1981, discussed above, is an example of admixing of coating materials with aspartame. This publication discloses the melting and admixture of from 20 to 60% of solid fat, 10 to 30% of polysaccharide and not more than 30% dipeptide sweetener. The mixture is then cooled and pulverized or spray dried. The pulverizing into fine powder, however, results in rupturing of the coating, leaving the aspartame exposed. Spray drying is normally associated with the driving off of moisture or solvents.
U.S. Pat. No. 4,597,970 discloses a delivery system wherein a sweetener is coated with a mixture of fatty acid or wax, lecithin and monoglyceride. The delivery system of this reference discloses a method of protecting the sweetener as well as providing controlled release.
The prior art techniques for coating difficult-to-coat materials such as aspartame has focused on two methods. The first method involves the formation of a molten mixture of the coating material with the sweetener. The mixture is then solidified by cooling and pulverizing. The resultant particles represent a random attempt at completely coating or enrobing the sweetener. In the case of aspartame, this coating does not provide adequate protection against moisture or aldehyde-containing flavor oils and instability of the aspartame results.
The second conventional prior art technique for coating materials involves fluidized bed spray coating. This technique involves suspending a mass of the material to be coated into a stream of atomized droplets of coating material. In the case where this process is employed with uncoated materials such as aspartame, this method is very difficult. Aspartame is a low density material, has a large surface to weight ratio and poor wetting characteristics.
In our co-pending application Ser. No. 945,743, it was proposed to prepare a sweetener delivery system comprising a sweetener such as aspartame dispersed in a melted and blended mixture of a low molecular weight polyvinylacetate and an emulsifier. The resulting dispersion is then cooled to ambient temperature and hardened, and thereafter ground to the desired particle size. Optionally, the particles thus prepared were coated with a hydrophobic mixture comprising a fat or wax blended with an emulsifier to provide, in effect, a discrete second coating to the sweetener composite. While the resulting composite exhibits improved stability, particularly when the subsequent coating of the fat/wax mixture is employed, the application of the latter coating tended to further delay sweetness release. This additional delay of release is undesirable in certain products, such as chewing gums and other confections, where a more immediate sweetness release is desired.
A further drawback in the use of the fat/wax second coating is that substantial amounts of this coating must be applied to the core particle to provide the required protection to the sweetener, particularly in the instance where the sweetener is aspartame. Thus, it has been found necessary to apply fat/wax coatings of about 300% by weight of the initial low molecular weight polyvinylacetate coating to confer the desired stability to the sweetener. The application of a coating of such thickness, even by the improved spray congealing methods utilized, is a relatively complex and involved procedure which naturally adds to the cost of the resulting product and consequently to products into which such sweetener composite may be incorporated.
A last concern respecting the composites prepared in accordance with co-pending application Ser. No. 945,743 by the incorporation of a subsequent coating of fat/wax, relates to the high temperature sensitivity of such a resulting composite. In particular, the fat/wax coating is more temperature sensitive and therefore the resulting sweetener composite cannot be employed in certain products such as baked goods or hard candies where higher processing temperatures are involved, without some concern that the outer coating of the composite will melt and thereby increase the risk that the sweetener will be attacked and broken down.
A need therefore exists for the preparation of a composite sweetener delivery system that can provide better stability to the sweetener with a greater initial sweetness release in combination with the delayed sweetness sensation conferred by the polyvinyl acetate core, all in further conjunction with improved stability including stability at high temperatures.